Torpedo



M. l. HULL TORPEDO 7 Sheets-Sheet 1 Filed Oct. 17, 1940 INVENTOR M. l. HULL TORPEDO Aug. 14, 1945.

Filed Oct. 17, 1940 INVENTBR '7 Sheets-Sheet 2 M. l. HULL Aug. 14,1945.

TORPEDO 7 Sheets-Sheet 3 Filed Oct. 17, 1940 ai 4; wa es? M. HULL. Z9SZ9G TbRPEDo Filed Oct. 17, 19,40 '7 Sheets-Sheet 4 ace [L] ///l ////////////////////////I/// Aug. 14, HULL TORPEDO Filed Oct. 17, 1940 7 Sheets-Sheet 5 m jip m/won TORPEDOI Filed Oct. IT, 1940 7 Sheets-Sheet 6 Alig, M. U 2,382,058 Q TORPEDO Filed Oct. 17, 1940 7 Sheets-Sheet 7 provide apparatus responsive to pedo'.

Patented Aug. 14, 1945 UNITED STATES PATENT OFFICE TORPEDO Maury I. Hull, Arlington, Va.

Application October 17, 1940, Serial No. 361,645

' 17 Claims. (01.114-23) The invention relates particularly to torpedoes which are guided by sound waves.

A principal object of my invention is to provide a torpedo which will have general utility, and which may be dropped from a parachute near an enemy vessel, or may be fired from a torpedo tube, or may be launched by dropping overboard from the deck of a surface vessel, or

maybe moored at'any desired point, where it a will wait until a vessel comes within range of its sound apparatus, when it will release itself from its mooring, and proceed toward its target.

A further object of my invention is to provide a torpedo which may be launched without respect to aim, and which when launched will select its target from any point on a 360 degree horizon.

A further object of my invention is to provide a torpedo which may be launched by parachute from aircraft.

A further object of my invention is. to provide a torpedo which can move in a vertical plane,

- and seek out submarines coming within range its mooring and so Figure 16 is a sectional view of the fuse of the trol motion in the horizontal and vertical planes, and the electrical circuits which control the steering apparatus.

Figure 2 is a diagram showing the light sensitive circuit, the listening microphone, and. the sound discriminating circuit.

Figure 3 is a radio control circuit.

Figure 4 is an illustration of the various arcs from which the four microphones shown in Figure 1 controlling the motion in the horizontal plane will respond to sounds, arcs I, II, III, and 1111 corresponding to micrdphones 2, 3, and 4 respectively.

Figures 5 and 6 are external views showing the location of the various microphones on the outside of the torpedo, and the rudders.

Figures 7 and 8 are sectional views of the rear portion of the torpedo showing the steering apparatus in more detail.

Figure 9 is a view of the arrangement of the various parts of the torpedo.

Figures 10, 11, 12, and 13 are views of the mechanism by which the parachute is attached to the torpedo, and the mechanism for releasing it when the torpedo reaches the surface of the water.

Figures 14 and 15 are illustrations of the mooring of the torpedo, and the mechanism for releasing it.

torpedo, and the mechanism for rendering it temporarily inoperative. a

provide apparatus responsive to sound waves for detaching the parachute from the torpedo.

A still further object of my invention is to light waves for rendering the torpedo inoperative.

Still a-iurther object of my invention is to provide a discriminating mechanism to control the manner in which light may affect Still a further object of my invention is to provide a discrimination mechanism responsive to radiant energy for rendering the torpedo temporarily inoperative so that friendly vessels may pass unharmed within range. I

Other objects of my invention will appear after a consideration of the tollowingde'scription taken in connection wit? the accompanying drawings, in which:

Figure 1 is a diagram showing the electrical circuits actuated by the microphones which con- .the tor- V Referring to Figure 1, microphones and 2, located near the front or head of the torpedo (Figure 5), excite thermionic tubes II and |2 respectively, which are biased by battery 3|. The plate circuit of tube includes resistance llll, battery 5|, and the audio filter consisting oi choke 4| and condenser 42. The plate circuit of tube l2 includes resistance I02, battery 52,

and the audio filter consisting of choke 4| and condenser 42. Tube H is coupled to tube 2| by coupling condenser 9|, and bias is supplied to tube 2| through resistance by battery 6|. Tube i2 is coupled to tube 22through condenser 92,. and bias is supplied to tube 22 through re-. sistance ||2-by battery 62. Battery H supplies the plate potential to both tubes 2|. and 22, the plate currents of the two tubes flowing through separate windings o1 thedouble polarized relay 20, and the combined plate currents 'ottubes 2| and 22 flowing through the winding m of differential relay-I0. I

Microphones and 2. are identical, except that 66 their patterns -01 directed to difler-- magnet I8 through battery 8|,

} left.

cut arcs as shown in Figure 4. Tubes II and I2, tubes 2I and 22, resistances MI and I02, batteries 5I and 52, batteries 6| and 62, and resistances I II and H2 are identical or of equal characteristics or values, so that when sounds reach microphones I and 2 in equal intensities, the plate currents of tubes 2| and 22 are equal.

The double polarized relay 20 has two windings. The plate currents flow through these windings in opposite directions, so that the magnetic fields tending to be set up as a result of the currents oppose each other, with the result that when the two plate currents are equal, the resulting magnetism is zero, and neither contact of the relay closes. The two armatures of the relay are permanently magnetized, so that they will be attracted to their respective ends of the core only when the poles of the relay core are of the proper polarity. As a result of this, only contact a will close when the plate current of tube 2| exceeds that of tube 22, and only contact b will close when the plate current of tube 22 exceeds that of tube 2|.

Contact a of relay 20 when closed energizes Contact b of relay 20 when closed energizes magnet II through battery 8 I.

Refer now to Figures 5 and 6, showing top and side views respectively of the torpedo, with the rudder 98 controlling motion in the vertical plane, hereafter to be called the vertical control rudder, and the rudder I01 controlling motion in the horizontal plane, hereafter to be called the horizontal control rudder.

Refer next to Figures 7 and 8 which show side and top sectional views respectively of the rudder control mechanisms. In Figure 8, magnet 58 when energized pulls rudder arm IIB toward It. moving rudder I01 (Figure 7) so that the torpedo if moving forward turns toward the right. Ma net I! when energized pulls rudder arm M5 toward it, tending to turn the torpedo toward the The rudder arm is normally held in a straight ahead position by springs I I7 and I I8. The propeller shaft passes above this portion of the rudder control mechanism, as shown in Figure '7. In Figure 8, the vertical control rudder 98 is moved by rudder arm H5. Magnets 8 and ill when energized pull the rudder arm down, making the torpedo turn downward. Turning again to Figure '7, magnet -9 when energized pulls the rudder arm up, turning the torpedo upward. Rudder arm H5 is normally held in a straight ahead" position by springs I09 and I III. Magnet 'I' shown in Figure l as being energized at the same time as magnet 9 is not shown in either of the sectional views for the sake of clearness, but would occupy a position parallel to and back of magnet 57 in Figure 7, and directly over magnet 8 in Figure 8.

Returning to Figure 1, if the microphones I and 2 and associated apparatus are identical or balanced, when the sounds reaching the two microphones are equal in intensity, the plate'currents of tubes 2| and 22 will be equal, and neither contact of relay 2!] will close. But if 'the sound reaching microphone I is greatest, contact a of relay 2O closes, energizing magnet I8, and making the torpedo turn to the right, while if the sound reaching microphone 2 is greater in intensity contact I) of relay 20 closes, energizing magnet I'I, turning the torpedo toward the left. For example, if the torpedo is moving directly toward its target, and the target then moves so that it is slightly to the right of the torpedos direction of motion, the sound reaching microphone I will become slightly greater in intensity than that reaching microphone 2, with the result that magnet I8 is energized, turning the torpedo toward the right until it is again pointed directly at the target, at which time the sound reaching microphones I and 2 again becomes equal, contact a of relay opens, and the torpedo straightens out. Had the target moved toward the left of the line of motion, magnet I! would have been energized as explained above, and the torpedo turned toward the left. In this way, the torpedo is kept pointed directly at the source of sound, which is the only direction of motion which will permit the sound to reach microphones I and 2 in equal intensity.

In Figures 5 and 6, a second pair of microphones 3 and 4 shown, placed on the torpedo. In Figure 1, these microphones 3 and 4 excite tubes I3 and I4 respectively, which are biased by battery 33. The plate of tube I3 is coupled to the grid of tube 23 in a manner similar to that described in the case of tubes II and 2I, and tube I 4 is similarly coupled to-tube 25. Batters 63 and 64 maybias tubes 23 and 2s at cut-oil respectively. Assuming switch 2I6 closed, the combined plate currents of tubes 23 and 2 3 flow through winding n of differential relay 30. This relay is so designed that as long as the current in winding it exceeds that in winding m, the relay contacts will remain closed. When the current in winding n equals or falls below that in winding m, the contact 0 is broken. This is to say that as long as the sum of the plate currents of tubes 23 and 24 exceeds the sum of the plate currents of tubes 2I and 22, the contacts are closed at c. When the contacts at c are closed magnet II is energized through battery BI moving the torpedo toward the left.

The switch H6 is provided in the plate circuits of tubes 23 and 24 to break the circuit of winding it when opened. The purpose of this switch will be disclosed subsequently.

Refer now'to Figure 4, which shows the directional characteristics of the microphones i, 52, and 4, the arcs of response I, II, III and 1117. belonging to the microphones respectively. Th 2tterns of response of the various microphones are not uniform within their respective arcs, but the microphones have their maximum sensitivity to sounds approaching from the center of the arc, the sensitivity falling oil uniformly on each side of the center until it reaches zero or app zero at the boundaries of the arcs shown by the dotted lines. These directional characteristics may be obtained by the desired shaping of an accoustical horn or sound chamber used to conduct sound to the diaphragm, or the directional characteristic might be inherent in the design of the microphone itself. The arcs of response of all of the microphones overlap at both ends.

Suppose now that the torpedo is launched from an airship, and lands so that the sound of its target approaches from the middle arc III. In that event, microphones I and 2 will not be excited, but microphone 3 will, hence more plate current will flow through winding 12. of relay 30 than will flow through winding 772. Contact 0 will close, exciting magnet I'I, causing the torpedo to turn in a counter-clockwise direction (Figure 4) or in other words, turn left. It will continue to turn in this direction until the sound approaches from are 1111. From this direction, also, microphones I and 2 are not excited, but the excitation ofmicrophone 4 causes the current in winding 11 of relay .30 to exceed that in winding 172, so that contactc remains closed, and the torpedo continues to turn left or counter-clockwise. It will continue to turn until the point Z on the arcs is reached, which point is included in both arcs II and H11. From this point the sound reaches both microphones 2 and 4. The plate current begins to rise in winding m of relay 36 due to the excitation of microphone 2 and tubes I2 and 22. Motion will continue in a counter-clockwise direction until the plate currents of windings m and n are equal, de-energizing the relay 36, and breaking contact 0. But at this moment I when contact of relay 36 breaks, contact b of ,relay 26 closes, for microphone 2 is being excited while microphone I is not, and because the plate current in'one winding of relay 26 due to the current in tube 22 exceeds that in the other winding of relay 26.

of -2I, only contact b closes. When contact b closes, it excites magnet I'I, turning the torpedo left or counter-clockwise It continues to turn until point Y is reached, that is, until the sound comes from the direction of Y. At this point, the sound reaching microphones I and 2 is equal, and contact b opens due to the de-energization of double polarized relay 26, as previously explained.

Resistances I63 and I04 are made variable so that the plate currents of tubes '23 and24 may be adjusted in relation to the plate currents of tubes 2I' and 22. 4

cult of Figure 1 is substantially as follows:

Microphone 5 excites tube I5 which is biased by battery 35. Microphone 6 excites tube I6 which is biased by battery 25. The plate circult of tube I5 includes resistance65, battery 36, 1 and the audio filter consisting of choke 45 and "condenser 46.

The plate circuit-oftube I6 includes resistance 66,,battery 36, and the audio filter consisting of choke 45 and condenser 46.

Microphones 5 and 6 have equal sensitivities and outputs, and'tubes I5 and "I6 are identical. Assuming that resistances 65 and 66 are adjusted to be equal, when sounds of. equal intensity reach microphones 5 and 6,- the plate currents of tubes I5 and I6 are equal. Since resistances '65 and 66 are made equal, equal voltage drops occur across them due to the currents flowing through them.

' The grid circuit of tube 25 consists of battery 55, and both resistances 65 and 66, as shown. The grid circuit of tube 26 consists of battery 56 and both resistances 65 and 66. The potentials of batteries 55 and 56 are alone suflicient to bias their respective tubes to cut-oil, or to the point where no or very little plate current flows. Relay 56 is energized when plate current flows in tube 25, and relay 66 is energized when plate current flows in tube 26, plate potential being supplied tubes '25 and 26 -by plate batteries I5 and I6 respectively. When relay 56 is energized, contact e closes, energizing magnets 6 and I6 through battery 65, and moving the'rudder 96 downward as previously explained, causing the torpedo to turn downward. When relay 66 is energized, contact g closes, energizing magnets I and 6 through battery", and moving the rudder' upward, causing the torpedo to turn upward. (SeeFlgures'landiLr As previously explained, when the plate current of tube 22 exceeds that Assuming now that the sound approaches from the same plane in which the torpedo is already moving. It reaches microphones 5 and 6 in equal intensities, causing equal plate currents in tubes 5 I5 and I6 and equal voltage drops across resistances 65 and 66. The voltage drop across re-.

sistance 65 tends to put a negative potential on the grid of tube 25, while the voltage drop across resistance 66 tends to apply a positive potential 10 to the grid of tube 25. These voltage drops being equal and-opposite in polarity, no effective voltage is introduced into the grid circuit-of 'tube 25, which remains biased to cut-oil by battery 55, and no plate current flows. Similarly, the voltage drop across resistance 66 tends to put a a negative potential on the grid of tube 26, while the voltage drop across resistance 65 tends to put a positive potential on the grid of tube 26. These voltage drops being equal and of opposite polarity, no eiiective voltage is introduced into the grid circuit of tube 26, which remains biased to cut-ofi, and no plate current flows.

For example, assume that when the sound was reaching microphones 5 and 6 in equal intensity, the peak plate current 0f tubes I5 and I6 were 10 milliamperes each. If resistances 65 and 66 are of 1000 ohms each, the peak voltage drops across each would be 10 volts.- Assume now that the sound source moves downward out of the plane of motion of the torpedo, and reaches microphone 6 with greater intensity than microphone 5. As a result of this the plate current of tube I6 becomes 12 milliamperes, while that of tube I5 falls to 8 milliamperes. The voltage drop across resistance 66 will now be 12 volts, while that across resistance 65 will-be 8 volts. These voltage drops are applied to the grid circuits of tubes 25 and 26. The eifective voltage introduced into the grid circuit of tube 25- is 12 positive minus 8 negative, or 4 peak volts of added positive potential or between 1 and 2 volts average,

reducing the bias of tube 25 to less than cut-oil,v

'causing plate current to flow, energizing relay 50, causing contact e to close, energizing magnets 6 and I6, and causing the rudder to move down,

I causing the torpedo to turn downward.

Under the same conditions mentioned above, when the voltage drop across resistance 66 was 12 volts, and that across resistance 65 was 8 volts, the effective voltage added in the. grid circuit of tube 26 would-be 4 peak volts or negative potential, increasing the bias of that tube beyond cutoff, and not energizing relay 66.

Similarly, if a sound came from above the plane of motion of the torpedo, it would reach microphone 5 in greater-intensity, causing current to flow in tube 26, energizing relay 66, causingcontact g to close, and energizing magnets I and 9 through battery 85, causing the rudder 66 to turn upward, causing'the torpedo to move u -ward Resistances 65 and 66 are made variable to permit of slightly unbalancing the circuit. It

the torpedo were operating in shallow water, the

- tacts, d on relay .66 and j on relay166. These contacts (1 and I are connected in parallel. The Y tubes in Figure -1.

torpedo as disclosed may be modifies. J) the inclusion in it of a device operated by water pressure to determine that the torpedo will travel at a certain distance under water, or at a certain depth under the surface. At 28 is shown an electrically operated device for rendering inoperative the depth-setting mechanism. 28 is energized through battery iii by contacts (1 or 1, so that the torpedo ma move upward or downward freely in response to differences in sound intensities reaching microphones and 5.

Three audio frequenc filters are shown in the circuit, at M and 42, as and M, and 4e and is.

These filters are included to minimize the effect upon the apparatus of the sound emanating from the torpedos own engine and propeller, and consist of parallel resonant circuits predesignedto be resonant at the dominant sound frequency of the engine. Since choke coils 4i and 43 carry the filament currents of tubes ii, 22, 23, and 24 as shown. they have low resistance windings. A further means of compensatingfor the sound of the torpedos engine is to increase the bias of tubes H and i2, and of tubes is and H, and of tubes and Iii or any of the other tubes of Figure l to the point where the sound of the torpedo's own engine is not sufliclent to cause substantial plate current increases, and only when an extraneous sound is added will the amount of plate current be sufiicient to operate the controlling mechanism. It is contemplated that the various batteries will be pre-designed to supply the correct potentials to bias all tubes as desired.

Relay l1 when energized closes contacts h, a, k, and l, lighting all the filaments of the various Battery 34 supplies the filament current for tubes H, 2i, I2, 22, I3, 23, H, and 24. Battery 31 supplies tube 25, battery 38 supplies tube 26, and battery as supplies tubes I5 and i6. Relay l! is energized as a result of the operation of the selector and listening" circuits of Figure 2, to be subsequently explained, wires XX in Figure 1 being connected to wires XX in Figure 2.

Relay H, and all other relays shown in the drawings and mentioned in the specification, unless otherwise stated,.. are of the conventional type, in which the armature is normally held away from the relay core by spring pressure until the relay is energized, when the armature moves toward the relay core, making or breaking contact, or both, as the se may be. When the relay is de-energized, t relay armature swings back to its former posit l.

A switch 5'! is includ .i in the grid circuit of tubes l5 and it, for making the vertical control rudder mechanism inoperative if it is desired that the torpedo respond only to surface targets. A switch 2 l 5 is provided as shown for short-circuiting the winding of relay 'l'i so that none of the filaments of the tubes of the sound-sensitive steering control circuits may be lit. As was previously stated, the torpedo is designed to have general utility, so that it may be fired from a torpedo tub'e aimed at its target, just as an ordinary torpedo is fired. In this event, no sound steering control is necessary or desirable. Switch 2l6 when opened breaks the circuit to winding-n of relay 30, rendering the microphones 3 and 4 impotent to influence the action of the torpedo, but leaving the control functions of microphones I and 2 unimpaired. It is contemplated that the torpedo may be fired from a torpedo tube in the general direction of its target, but not aimed exactly. Microphones! and '2 pick up the sound of the target, and steerthe torpedo toward it,

as previously explained. Microphones 3 and 4 are rendered impotent by opening switch 2|6, so that the direction of the torpedo will not be infiuenced by the sounds coming from the submarine or vessel discharging it, and so that the torpedo will not turn and destroy the-vessel or craft firing it. As will be explained subsequently, when the torpedo is fired from a torpedo tube, a latch switch on the outside of the torpedo is tripped, energizing relay 11 if switch 215 is open. By the time the filaments of the tubes of Figure 1 have heated to normal emission, the torpedo has moved some distance from the vessel firing it.

Refer now to Figure 2, a selector and discriminating circuit, One use of the invention disclosed herein contemplates that the torpedo may be moored at a desired point, and left until an enemy vessel comes within range of its sound apparatus, when the torpedo will release itself from its mooring, and proceed to its target. During this inactive period, it is essential that as little current as possible be drawn from the batteries in the torpedo. For that reason, in the present invention, a separate non-directional microphone'is included, associated with a vacuum tube which may remain turned on all the time, the filaments of the tubes of the rest of the rudder control mechanism being turned off. When the listening" microphone detects a sound, a sound which the discriminating circuit will allow to operate the proper relays, the filaments of the other tubes associated with the directing microphones are lit, the power to the motor driving the propeller is turned on, and the torpedo is released from its mooring.

The microphone 21 is placed upon the bottom of the torpedo as shown in Figure 6. It delivers its output to tube 58 of Figure 2, which is biased by battery 49 to act.as a rectifier. Tube 58 is normally biased by battery 49 so that without excitation of microphone 21, the plate current is insuflicient to energize and operate relay 69-when switch 20! is closed. Plate potential is supplied to tube 58 by battery 68, and filament potential by battery 61. Included in the filament circuit is switch 59, which permits the filaments of both tubes 58 and as to be turned off and on.

7 The circuit comprising tube 80 is essentially an electronic timing means. Relay 65 has three sets of contacts,.o, p, and q, so arranged that q makes contact when the relay is energized, while 0 and 13 break contact when the relay magnet is-energized. When the magnet is tie-energized, the armature returns to its original position as explained previously. The spacing of the contact the conventional type'unless otherwise stated, in

which the armature is normally held away from the relay core by spring tension, moving toward it when the relay is energized, and moving away from it when the relay is [dc-energized. Relay 88 has two contacts t and u, which are latched closed by the latch 81 so that when relay 88 is tie-energized, contacts t and u do not break until the latch is tripped by energizatlon of the latchtripping coil 88. A switch 283 is provided for shorting contact u. Relay 89 has two contacts and w, both of which make when the relay is energized, and open when it is de-energized.

At 41 is shown a light-sensitive device which may be a photo-conductive cell, which, when light reaches a certain intensity, energizes sensitive relay 48 through battery 48. A switch 29 is included for rendering the light-sensitive circuit inoperative when desired. When relay 48 is energized, it breaks the relay contacts opening the circuit of microphone 21, and rendering the selector and listening mechanism inoperative. The light-sensitive cell 41 is mounted on the outside of the torpedo as shown in Figures and 6.

The operation of the circuit of Figure 2 is substantially as follows: When switch 29 is open, switch 282 is open, switch 283 is open, switch 28I is closed, and switch 59 is closed, microphone 21 picks up a sound, causing plate current to flow in tube 58 and relay 89 is energized. Contact q closes, permitting'current from battery 84 to flow through resistance 19 charging condenser 18. If the sound continues unbroken for a suflicient time, condenser 18 is sufliciently charged to place a sufllcient voltage on the grid of tube 88 to permit the requisite plate current to flow in tube 88 to energize relay 88, the elapsed time depending upon the value of the resistance 18 and the capacity of 18, for a given value of battery 84. If the sound doesnt continue for a sufiicient time to operate relay 88 as above, whenrelay 89 is de-energized, contact makes, discharging by shorting through the lower point of contact 1 and contact s of, relay 18 the condenser 18, so

engines.

Assuming that the sound has continued for the required time, and relay 88 has been energized. Contact u is made, and if the circuit containing contact u, relay 89, battery 98, relay 11 (Figure 1) and thecontacts of relay I12 in Figure 3, and connected by wires IT in Figures 2 and 3, is not broken due to the energization of relay I12 by the radio controlled apparatus shown in Figure 3, thenrelay 11 is energized and the filaments of .the rudder control mechanism of Figure 1 are lit, setting these circuits in operation, and relay 89 is energized, closing contacts '1) and 10 which complete the battery circuits supplying power to 99 and I88. 99 is an electrically operated valve for turning on the compressed air or other power to the motor driving the propeller, and keeping it on as long as contact w remains closed. This electrically op-' erated valve, shown in Figure 9, may be of any desired design, and may consist of a cylinder or rod which is normally held by spring tension in such a position that it-closes the port, with a magnet'arranged to move the rod when energized.

made, and latch 81 closes, so that contacts t and u remain closed when relay 88 is de-energized. Contact t closes the circuit energizing relays 18,

12, and 82 through battery 83. As a. result of these energizations, the armature of relay 82 makes contact with the inside or left-hand con,- tact point, connecting the output of tube 88 to the latch-tripping coil 88. The contacts of relay 12 should be faster than those of relay 82. The contacts of relay 12 close, connecting condenser 14' in parallel with condenser 18 and thereby increasing the time period of the electronic time tacts making and breaking at relay 18 is to convert the circuit of tube 88 into a time delay relay which is responsive to the de-energization of relay 89. When relay 89 is de-energized, contact o is made, sending the charging current of battery 84 through resistance 19 until condensers 18 and 14, now in parallel, are charged sufliciently to permit enough plate current to flow in tube ,88 to excite coil 88, tripping the latch 81, and opening contacts t and u.

Switch 28I when opened disconnects the plate of tube 58 from relay 89, and the switch 282 is provided for connecting the output of tube- 58 directly to relay 88, so that any time delay between the picking up of the sound by microphone 21 and the energization of relays 11 and 89 through the closingof contact u of relay 88, is avoided. If the torpedo were to be dropped from a plane directly over an enemy ship in motion, it would be desirable that the torpedo proceed toward its target immediately after striking the water. Switch 283 bridging contact u of relay 88 is provided for shorting out the listening mechanism, so that the direction control apparatus may be turned on instantly. The switch 283 is a latchswitch on the outside of the torpedo, designed to be tripped k closed as the torpedo is discharged from a regular torpedo tube.

Figure 3 shows the device responsive to radio signals for rendering the torpedo temporarily inoperative, so that a friendly ship, bysending out the required radio transmissions, might traverse an area in which the torpedoes had been moored without harm.

Two antennae are provided on the outside of the torpedo at I85 and I88 as shown in Figure 5,

sisting of inductance I24 and condenser I28. At

I21 is a double-triode vacuum tube acting as a rectifier, and having a filament, two grids I38 and I31, and two plates I35 and'l38. The grid I38 is connected to one side of tuned circuit I23I25, and the other side of this tuned circuit is connected to the filament of tube I 21. .The grid I 31 is connected as shown to one side of the tuned circuit I24-428, the other side of this tuned circuit being connected to the filamentpf tube I21. Plate I 35 is connected to a radio frequency filter consisting of choke I28 and by-pass condensers I29 and I38, the center or common connection of the by-pass condensers being connected as shown to the filament of tube I21. The .equal resistancesI3I, I32, and I34, and audio frequency choke coil I33 comprise a bridge circuit, which will be unbalanced except at that 811C110 frequency whichmakes the impedance of choke I33 equal to the resistance of the three-re- Two leads are taken from the centers are connected to the coil of relay I53 as shown, energizing this relay when a sufl'icient diil'erence of potential exists within the bridge.

Similarly, plate I38 of vacuum tube I21 is connected to a radio frequency filter consisting of choke MI and by-pass condensers I39 and I40, the center or common connection of the by-pass condensers being connected as shown to the filament of tube I21. The equal resistances I42, I43, and I45, and audio frequency choke coil I44 comprise a bridge circuit, which will be unbalanced except at that audio frequency which makes the impedance of choke I44 equal to the resistance of the three resistances I42, I43, and I45. Two leads are taken from the centers of the bridge as shown, and through switch I I9 are connected to the coil of relay I54, energizing this relay when a difference of potential exists within the bridge.

The relay I 50 is a differential relay designed to operate and influence contacts A, B, and C only when the current in either one of its windings exceeds that in the other. The plate current of plate I35 of tube I 21, in flowing through its radio frequency filter and audio frequency bridge as shown, flows through the upper winding M of relay I50. The plate circuit of plate I35 is thence completed through the winding of relay I52 and plate battery I41, and thence to the filament of tube I21. The plate current of plate I38 of tube I21, in flowing through its radio frequency filter and audio frequency bridge as shown, flows through the lower winding N of relay I50. The plate circuit of plate I38 is thence completed through the winding of relay I51 and plate battery I41, and thence to the filament of tube I21. Relays II and I52 make contact when they are energized, while relays I53 and I 54 break contact when they are energized. Battery I46 supplies the filament potential for tubes I21 and I58 as shown, and may be cut out of the circuit by switch I69.

Tube I58 is an electronic time delay circuit whose time constant is determined by the values of resistance I48 and condenser I51. Battery I49 supplies the charging potential, the current from which flows through resistance I48, the contacts of relays I54, I53, I52, I5I, and I50 at contact C. Tube I58 has its plate connected to the armature of relay I64, which is normally held by spring tension against the lower contact, so that plate current of tube I58 flows through relay I68 and plate battery I65, with the result that when the voltage on condenser I51 has built up sufficiently, sufiicient plate current flows in tube I58 to energize relay I68. When the armature of relay I64 is against the upper contact due to the energization of the relay winding, the plate of tube I58 is connected to coil I61,'as shown.

The relay I68 has three sets of contacts, F, G, and H, all of which make when the relay is energized. A latch I is provided so that the contacts are not broken when the relay is 'de-ener-v gized. Two tripping coils I66 and I61 are rovided,'the energization of either of which will-release the latch, opening all three contacts. One tripping winding I61 is designed to be energized by the plate current of tube I58 when the armature. of relay I64 is held in an upward position due to the energization of relay I64 as previously described. The other trippin coil I66 is energized through battery I63 when the contactsv of time delay relay I62 are closed. Time delay relay I62 maybe of any desired type, and may depend for time delay action upon the movement of air. The circuit for energizing time delay relay I62 includes contact A of relay I 50, battery I60, and contact G of relay I68.

The contact F of relay I68 when closed energizes relays I59 and I64 through battery I6I, as shown.

The function of contact H of relay I68 will be disclosed subsequently.

Relay I59 has two sets of contacts, as shown, contact D breaking when the relay is energized, and contact E making when the relay is energized. Contact E when closed connects condenser I56 in parallelwith condenser I51. Condenser I56 is somewhat smaller in capacity than condenser I51, the exact capacity depending upon a time factor to be disclosed subsequently. Contact D of relay I59 influences the circuit in a manner to be subsequently explained.

Relay I50 has three sets of contacts. Contact A breaks when the relay is energized. Contact B breaks when the relay is energized. In the third set of contacts C, the armature makes contact with-two points, one point when the relay is energized, and the other point when the relay is de-energized.

The contact H of relay I68 when closed energizes relay I12 through-battery "I, which remains energized as long as contacts H remain closed. When relay I12 is energized, its contacts break, breaking the circuit of Figures 1 and 2 which consisted of relay I1, battery 96, contact u of relay 88, and relay 89. The result of breaking this circuit is that the filaments of the tubes of the sound steering control are turned off, and the power to the propeller is turned off at 59. If switch 204 is closed, magnet I96 is also energized through battery I1I when contact H of relay I88 is closed. Magnet I96 when energized operates a mechanism which renders the fuse of the torpedo inoperative, as subsequently disclosed, and as shown in Figure 16.

Having traced the various circuits associated with tube I58, the operation of the circuits of Figure 3 can be best understood in reference to the purpose of the circuit, which is to provide a means whereby a ship, by sending out a continuous radio signal or signals, can render the torpedo driving and steering mechanism, and iuse, inoperative. To accomplish this, the radio signals must result in the energization of relay I68,

but must not energize tripping coils I66 or I61. Another purpose is to provide means which are to a degree secret and diflicult to analyze by an enemy. To accomplish this latter purpose, means are provided for discriminating between radio signals with respect to amplitude, with respect to modulation, and with respect to time, so that only signals having predetermined qualities will operate the relays properly.

Assuming switches I69, IIS, and I20 closed, and I2I and I22 open, amplitude discrimination is accomplished by differential relay I50, which is designed to operate only when the current in one of its windings exceeds substantially that in the other. The upper winding M is'energized by the plate current of plate I35 of tube I21 and is proportional to the intensity of the signal received on antenna I05, in accordance with well established and known laws of radio frequency rectifying circuits. Similarly thelower winding N of relay I50 is energized by the plate current of plate I38 of tube I21, and is proportional to the intensity or amplitude of the signal received on antenna I06. The reason two signals are necessary under theconditions specified (that is, switches I2I and current of plate I35. Switch l2I is provided for shorting the contacts of relay I5I, and switch I22 is provided for shorting the contacts of relay I52. When both these switches are closed, neither relay I5I or-l52 need be energized, to complete the circuit I49-I48-I51. Since relay I50 will operate contacts A, B, and C when only one antenna is furnishing a signal, this switch arrangement will permit of some secrecy, for the timing circuit of tube I58 is designed to respond only to dashes and spaces having definite time relationships, and one dash might be sent on one wavelength to antenna I05, and the next dash on the other wavelength to antenna I06, and soon, making it diiflcult for the enemy to analyze the required transmission and discover the secret'code, especially so since the dashes after the first dash do not need'to be of any exact length, so long as they are less than a certain length, and a definite time relationship is maintained between the dashes and spaces.

The modulation discriminating function is accomplished by the two audio frequency bridges,

the one in the circuit of plate I35 comprising equal resistances I3I, I32, and I34, and inductance I33, and the bridge in the circuit of plate I38 comprising .equal resistances I42, I43, and

I45, and inductance I44. As previously explained,

these bridges will be balanced only when their respective radio frequency sources of energization are modulated at audio frequencies at which the impedances of the inductances are equal to the resistances associated therewith. Assuming switcheslI9 and I20 closed, relay I53 will be energized when a sufficient difference of potential exists across the bridge in the plate circuit of I35, and relay I54 will be energized when a suiiicient difference of potential exists across the bridge in the circuit of plate I38. Both of these relays have their contacts in the circuit of the timing mechanism (in the circuit of the grid of tube I58), and both contacts must be closed for the proper functioning of the timing circuit. Energization of either relay breaks its contacts. Hence the energization of either of the relays I53 r I54 due to modulating the radio signals at improper audio frequencies, will render the timing circuit inoperative by opening it. Switches H9 and I20 are provided .for rendering the modulation discriminating circuits inoperative, if desired. When these switches are opened, relays I53 and I54 are rendered inoperative.

The timing circuit operates as follows: Assume that it is desired to provide that a continuous code signal consisting of a first dash seconds long will render the torpedo inoperative. Assume that the radio signals sent are of the proper amplitude and modulated properly to pass the amplitude and modulation discriminating circuits. energize relays I50, I5I, and I 52. The armature of contact C of relay I50 closes with the lower point, completing the circuit containing battery I 49, resistance I48, and condenser I51. The condenser and resistance-are so chosen that it will take just five seconds for the condenser to charge sufliciently to put a sufiicient voltage on the grid Then when the first dash begins, it will of tube I58 to. allow suflicient plate current to pass to energize relay I68. i

Assume for the moment that-the dash lasted only 4 seconds.

5 when the dash ends, the armature ofcontact C swings back making contact with the upper point.

.Thispoint is connected as shown with contact D of relay I59, which contacts are closed when the relay I59 is notenergized. The armature of D of relay I59 is connected as shown to a point between battery I49 and condenser I51, with the result that when relay I50 is de-energized, condenser I 51 is discharged by short-circuiting it, through contact C of relay I50 and contact D of i5 relay I59.- At the same moment that the deenergization of relay I50 causes condenser I51 to be shorted and discharged, the armature of C swings away from its lower point, breaking the battery circuit of battery I49. is provided for making the mechanism responsive to a first dash of at least a certain length.

Assume now thatthe dash continues for the necessary five seconds'to energize relay I68. At the 5 second point, contacts F, G, and H of relay 2:, I68 are closed, and latched. Contact H energizes relay I12 as previously explained. Contact G although closed does not energize time delay relay I62 immediately, because contact A of relay I50 is broken when I50 is energized. Contact F of an relay I68 energizes relays I64 and I59 through contacts of relay- I68 are unlatched. Relay I64 pulls its armature upward, connecting the output of tube I58 to the latch tripping coil I61. Relay- I59 opens contact D and closes contact E which I51. There is an immediate drop'in voltage across condenser I51 as a result, causing the plate current of tube I58 to fall, with the resultthat trip 4 ping coil I61 is not immediately sufflcientlyenergized to trip the latch I10 of relay I68. Itis essential to the proper operation of the circuits /"*that the contacts of relay I64 be slower than those of relay I59, for condenser I56 must be connected an instant before coil I61 is connected into the circuit, otherwise the grid voltage of tube I58 would not fall, the plate current of tube I58 would not fall, and coilv I61 would be energized the imstant the armature of relay I64 touched the upper contact, tripping the latch of relay I68. Hence if the dash stops at five seconds, contact H of relay I68 remains closed, and the power to the torpedo remains turned off.

.Assume now that the dash lasted longer than five seconds. After relay I59 has been energized, condensers I56 and I51 in parallel'continue to be charged through resistance I48 until they place a sufiicient voltage on the grid of tube I58 to allow sufllcient plate current to flow to energize coil 60 I61, tripping the latch, resulting in the'turning on of the torDedos power. So that the mechanism has been made responsive only to a first dash of less than a certain duration.

The circuit also operates to insure that only spaces of the proper length between dashes, will cause the power to the steering, propelling, and releasing mechanisms to remain cut on. If the spaces are either too short or too long, the power will be turned on. This is brought about in the following manner: Assuming that the dash ended after five seconds, the contacts F, G, and H of relay I68 remaining latched. When relay I50 is de-energized due to the stoppage of the signal, contact A makes, completing the circuit containing tiniegdelay relay I62 and battery I60. If the Then relay I50 is de-energized Hence a v means battery I6I, keeping them energized until the puts condenser I56 in parallel with condenser space continues long enough, say two seconds, to energize the time delay relay I82 completely, its contacts close, energizing latch tripping coil I06 through battery I03. This trips the latch I10, resulting in the turning on of the torpedo power, and steering apparatus. But assume that the space did not last long enough to close the contact of relay I 62. When contact A of relay I50 is broken at the beginning of the next dash, relay I62 returns 'to its normal de-energized position. Since the dash is longer than the space, any air has time to be replaced in relay I02, or temporary residual magnetism or currents to subside. Hence the space between dashes can not exceed a certain value.

If the space between dashes is not long enough, the latch will be tripped. When the dash stops, a charge remains on condensers I51 and I56. Assuming that the dash was of the correct length to energize relay I68 but not to unlatch I10, then the de-energization of relay I50 closes contact B, which connects resistance I55 across the two condensers. The value of this resistance is chosen so that it will just discharge the condensers completely in the time of the desired space. If the space is not long enough, the condensers will not be fully discharged during the-space, and when the next dash begins, it will find some residual charge on the condensers, and the plate current of tube I58 will build up in less time than calculated to a value suflicient to energize coil I61 tripping the latch I10 of relay I88, resulting. in the power being turned on to the torpedo motor and steering apparatus.

. After the first dash, the dashes can be of any length less than the time required to trip the latch I10, provided the spaces are sufllciently long each time to discharge th condensers. The

spaces can not be too long or relay I62 will operate to restore the power to the torpedo.

When the ship has passed, all that is necessary to replace the torpedo in its former condition of a waiting is to stop the transmission of radio signals. The first space exceeding the time, or equaling thetime, required to close the contact of relayl62 energizes coil I86 tripping the latch r'he effective range of the ship's radio apparais should exceed the effective range of the toredos sound apparatus,

Figure 9 is a plan view of the inside of the torpedo, showing the placing of the various parts. Section K contains the explosive, section L-contains the batteries and electrical equipment. Section L isso designed that batteries 81, S8, and 40 of Figure 2, and batteries I45 and I41 of Figure 3 comprise a separate compartment easily accessible. A plate may be screwed over an opening in the wall of the torpedo through which these batteries may be moved. These are the only batteries on which there will be a constant drain whether the torpedo is in operation or not, and proper biasing will reduce the drain of the plate batteries. It is contemplated that the torpedo,

when moored' to one spot,niay be periodically serviced," by replacing the batteries mentioned with new ones. Section P contains the tank of compressed air, and sectionQ contains the propeller driving motor or engine and associated apparatus. The engine may be an air-driven turbine or any convenientdevice. The electrically operated valve 99 joins sections P and Q, operating as previously disclosed. Section W contains the steering apparatus, shown in detail in Figure 7 and 8.

Refer now to Figures 10, 11, 12, and 13, which show views of the mechanism for attaching the torpedo to a parachute, and releasing it. In Figure 10, the lever I13 is a wide, thin lever attached to the side of the torpedo 200 as shown. Attached to the lever is a pin I14. This mechanism is attached to the torpedo on that side of its center of gravity which will determine that the torpedo in descending strikes the water from such an angle as to cause the lever I13 to move toward the right (in Figure 10). The dotted lines show the lever and pin folded into the position they will occupy after the torpedo has assumed its normal motion through the water. Figure 13 shows the parachute I15, a light chain I15 attached to it, and the shackle I11 attached to the end of the chain.

Figure 11 is a view of a part of the mechanism,

looking along the surface of the torpedo. On the side of the torpedo are three collars I80, I8I, and I82. A bolt H8 passes through these, and also through shackle I11 as shown. A spring I19 is provided which tends to eject the bolt from the collars. Figure 12 shows a section of the mechanism, showing the pin I14 passing through a loosely fitting collar I83 and into a groove cut in the bolt I18. The action of the mechanism disclosed in Figures 10, 11, 12, and 13 is substantially as follows: When the torpedo is prepared to be launched by parachute, shackle I11 is placed in position, and bolt I18 pressed against the spring I19 until the bolt passes through the collars and the shackle. The lever I13-is raised, forcing pin I14 into the groove'of bolt I18, holding the bolt in position passing through the collars and shackle. When the torpedo strikes the water after descending, the force of the water moves lever I13 back, withdrawing pin I14, whereupon spring I19 causes bolt I18 to spring to the right in Figure 12, releasing the shackle.

Refer now to Figures 14 and 15, which show the method of mooring the torpedo. In Figure 15, a floating o'r submerged buoy 2 is attached by rope 2I2 to an anchor 2I4. Rope 206 goes from the buoy to the torpedo, and is attached by the mechanism shown in section in Figure 14. The rope 206 is attached to the eyebolt 205 which pases through two collars I98 and I99 attached.

to the side of the torpedo 200. Inside the torpedo, placed as shown, is iron rod 209 having a flange 201, and arranged to engage a groove in the bolt 205. The rod passes into a solenoid I00 as shown. The rod 209 is normally held in the groove of bolt 205 by the action of spring 208 as shown, but when the solenoid is energized, it pulls the rod downward or inward compressing the spring and enabling the bolt to slip out of its collars. Magnet I00 is energized from a battery as shown'in Figure 2. Atthe same moment that the solenoid I00 is energized, the valve 99 is turned on as previously described and as shown in Figure 2, and causes the torpedo to move forward causing the bolt to slip from the collars. Figure 15 shows a side view of the torpedo, with the eyebolt 205 in place in its collars.

Refer now to Figure 16 which shows a sectional view of the contact fuse or percussion fuse mentioned previously. As was stated formerly, the torpedo is designed so that a friendly vessel, by emitting asecret radio signal or signals, may safely traverse an area in which the torpedoes had been moored. This radio wave renders the steering control apparatus and the torpedo motor inoperative as previously explained, and also renders the fuse mechanism inoperative so that if the vessel struck the torpedo from a certain angle, it would not necessarily explode. In Figure 16, the striker head is shown at I84, to which is attached the firing pin I88. The striker head is normally held as shown by the pressure of spring I85, but whenthetorpedo strikes its target,

supported as shown on support I94. Inside the solenoid is a rod I95, normally held in the position shown by the action of spring I93. The rod is made of two parts, joined in any convenient manner. Part S is of a magnetic material, part R being of a nonmagneti material. When solenoid I96 is energized, part S is drawn inward or to the left, forcing the rod toward the. left, in which position it prevents the firing pin from moving by holding the flange I92 of the firing pin against the rib I81 of the fuse body. The

solenoid I96 is energized from battery III as shown in Figure 3. Switch 204-is provided for cutting the solenoidout of the circuit when desired.

It is not necessary that the arcs of response of the various microphones I, 2, 3, and 4 cover exactly that portion of the 360 degrees as shown in Figure 4. For example, the arcs of microphones 3 and 4 might extend somewhat farther forward, or the arcs of microphones I and 2 might extend toward the rear of the torpedo.

It is likewise not necessary that the patterns of response of microphones I and 2 be exactly identical, but they must provide exactly equal outputs when excited by any sound coming from directly in front of the torpedo.

It is contemplated that dynamic type microphones be used in the drawings and Specification as disclosed, but it is not intended to limit the invention thereby. Where tubes 25 and 26 have been described as normally biased to cut-off, these tubes could be biased at less than cut-off, but

biased at a point where sufficient plate current to operate the relays in their plate circuits flows only when a difference of sound intensities reach microphones 5 and 6.

While the various antennae, microphones, light-sensitive cell, and apparatus for attaching the torpedo to a parachute or buoy, and some of. the rudders, are shown as protruding beyond the plane of the normal surface of the torpedo, it is not intended to limit the invention thereby to the use of such apparatus. These parts which .now protrude might all be placed in grooves, slots, or indentations below the plane of the surface, so that the torpedo may be fired from a regular shaped torpedo tube.

It is contemplated that all of the switches except switch 293 of'Figure 2 be brought to a common terminal board, either on the surface of the torpedo, or hich' may be reached by unscrewing a plate, so that the various desired combinations of switches may be closed or opened, depending uponwhether the torpedo i to be launched by tube, parachute, or moored, and whether the light-sensitive circuit, or the listening circuit, or the radio control circuit, or other circuits or elements are to be used, and in wh'at manner. Switch 203 .of Figure 2 is a latch switch arranged to be tripped as the torpedo is shot out of its tube. It turns on the power to the torpedo propeller immediately, and, if desired, turns on the sound controlled steering apparatus immediately, after a brief interval in which the'filaments of the various tubes warm up.

It is contemplated that the torpedo might be used to guard a certain shipping lane during the night, in which case it would be moored nearby. When daylight came, the light sensitive cell would render the listening microphone inoperative, and

ditional winding on relay I50 may be provided for each additional wavelength. In this Way, the proper operation of the timing circuit of tube I58 would be made dependent on simultaneous transmissions on more than two wavelengths, or, if all the contacts of the additional relays were shorted by closing switches corresponding in function to switches I2I and I22, relay I50 being responsive to transmissions on any one of the wavelengths, the series of dashes required to maintain the contacts of relay I68 closed could be sent on more than two alternate wavelengths, making it more difficult for an'enemy to discover the secret of the transmissions.

Other modifications are possible, and I therefore do not wish to be limited to the precise details of the invention as set forth herein, except as required by the claims which follow.

I claim:

1. In a torpedo, steering apparatus comprising rudders and moving means for turning said rudders, control means for said moving means adapted to be electrically operated, a source of power for said control means, a pair of microphones, a first relay having a pair of windings each carrying current substantially proportional to the intensity of sound reaching one of said pair of microphones, a third microphone, a second relay having a first winding and a second winding, the first winding of .said second relay carrying a current substantially proportional to the intensity of sound reaching said third microphone, the second winding of said second relay carrying current proportional to the intensity of sound reaching at least one of said pair of microphones, the contacts of said first and said second relays controlling the application of said source of power to said control means.

2. In a torpedo, steering apparatus comprising rudders and moving means for turning said rudders, control means for said moving means adapted to be electrically operated, a source of power for said control means, a pair of microphones, a thermionic rectifier associated with each microphone of said pair wherein the rectified current is substantially proportional to the intensity'of pedo in a horizontal plane, a second rudder mechanism for turning the torpedo in a vertical plane, first and second moving means for'turning said rudder mechanisms, first and second control means for said moving means adapted to be electrically operated, at least one source of power for said first, and second control means, a first pair of microphones, a first relay having a pair of windings each carrying current substantially proportional to the intensity of sound reaching one of said first pair of microphones, a third microphone, a second relay having a first winding and a second winding, the first winding of said second relay carrying a current substantially proportional to the intensity of sound reaching said third microphone, the second winding of said second relay carrying current proportional to the intensity of sound reaching at least one of said first pair of microphones, the contacts of said first and said second relays controlling the application of said source of power to said first control means; a second pair of microphones, a thermionic rectifier associated With each microphone of said second pair wherein the rectified current is substantially proportional to the intensity of sound reaching the microphone associated therewith, resistance means connected with each of said rectifiers, relay means, means rendering said relays means controlled by the difierences in potential existing across said resistance means, the contacts of said relay means controlling the application of said source of power to said second control means.

l. In a torpedo, the combination of rudders, moving means therefor electrically operated; a plurality of microphones, a first electric circuit normally inoperative including at least one thermionic tube connecting said microphones with said moving means whereby said rudders are adapted to be moved in response to sounds reaching said microphones, at least one source of power for said thermionic tube, and a second electric circuit energized directly from one of said microphones including means for controlling the application of said source of power to said thermionic tube whereby sounds actuating said second electric circuit cause said first electrical circuit to become operative to control said rudders.

5. In a torpedo having propelling and steering mechanism, means for attaching the torpedo to an object external thereto comprising a first member adapted to catch with a suitable adjacent external member, a solenoid adapted to release said first member when the solenoid is energized, a source of power for said solenoid, a

circuit connecting said source of power and said solenoid, a relay, the contacts of said relay being in the said circuit of the source of power and solenoid, said relay acting when energized to apply power to said solenoid, a microphone, and means rendering said relay energized upon the receipt of sounds of at least a predetermined duration by said microphone to close said circuit and release said torpedo.

6. In a, torpedo having steering means, propelling'means and a source of power for said propelling means, electrically operated control means for starting said propelling means and a. source of power for said electrically operated control means; means for attaching the torpedo to an object external thereto comprising a first member adapted to catch with a suitable external member, a solenoid adapted when energized to release said first member, a. source of power for said solenoid, a relay having contacts which close when the relay is energized the contacts oi said relay controlling the application of power to said propeller control means and the application of power to said solenoid, a microphone, and means rendering said relay energized upon thereceipt of sounds of at least a predetermined duration by said microphone to effect the starting of the propelling means and the releasing of the torpedo.

7. In a torpedo, rudders, moving means electrically operated for turning said rudders, relay means for controlling said moving means, a plurality of microphones disposed on said torpedo and adapted to be actuated by sounds reaching said torpedo from an external source, means rendering said relay means actuated by difierences in sound intensity reaching pairs'of said microphones to effect the steering of the torpedo,

said last mentioned means including at least one thermionic tube and at least one source of power for said tube, a first relay, the circuit of said thermionic tube and said source of power-including the contacts ofsaid first relay, said first relay acting when energized to close its contacts, a source of power for said first relay, a second relay and a third relay, the circuit of said last mentioned source of power and said first relay including the contacts of said second relay and the contacts of said third relay, said second relay acting when energized to close the circuit supplying power to said first relay, said third relay acting when energized to open the circuit supplying power to said first relay, means rendering said second relay actuated by sounds reach ing one of said microphones to cause the energization of said first relay and the application of power to said thermionic tube, radio receiving means, means rendering said third relay actuated by said radio receiving means to open the circuit supplying power to said first relay, whereby when said radio receiving means is energized by a radio signal of predetermined character, sounds reaching said torpedo are prevented from causing the application of power to said thermionic tube.

8. In a torpedo, propelling means, a source or" power for said propelling means, electrically operated control means for starting said propelling means including a first relay, said first relay acting when energized to start said propelling means, a source of power for said first relay, a second relay and a third relay, an electrical circuit connecting said source of power with said first relay including the contacts of said second relay and the contacts of said third relay, said second relay when energized acting to close its contacts, said third relay when energized acting to open its contacts, a microphone, means rendering said second relay energized when sounds of at least a predetermined duration reach said microphone, radio receiving means, and means rendering said third relay energized when said radio receiving means are energized by a radio signal of predetermined character.

9. In a torpedo having propelling and steering mechanism, means for attaching the torpedo to an object external thereto comprising a first member adapted to catch with a suitable adjacent external member, a solenoid adapted when energized to release said first member, a source' of power for said solenoid, a circuit connecting said source of power and said solenoid, a first relay, the contacts of said first relay being in the circuit of said solenoid and said source of power, said first relay acting when energized to close its contacts, a source of power for said first relay, 2. second relay and a third relay, an electric circuit connecting said' source of power with said first relay including the contacts of said second assaoes relay and the contacts of said third relay, said second relay when energized acting to close its contacts, said. third relay when energized acting to open its contacts, a microphone, means rendering said second relay energized when sounds of at least a predetermined duration reach said microphone, radio receiving means, and means rendering said third relay energized when said radio receiving means are energized by a radio signal of predetermined character.

10. In a torpedo having steering means, propelling means and a source of power for said propelling means, electrically operated control means for starting said propelling means and a source of power for said electrically operated control means; means for attaching the torpedo to an object external thereto comprising a first member adapted tocatch with a suitable external member, a solenoid adapted when energized to release said first member, a source of power for said solenoid, a first relay, the contacts of said first relay closing when the relay is energized and applying power to said propeller control means and to said solenoid, a source of power for said first relay, a second relay and a third relay, an electric circuit connecting said source of power with said first relay including the contacts of said second relay and the contacts of said third relay, said second relay when energized acting to close its contacts, said third relay acting when energized to open its contacts, a microphone, means rendering said second relay energized when sounds of at least a predetermined duration reach said microphone, radio receiving means, and

means rendering said third relay energized when said radio receiving means are energized by a radi signal of predetermined character, whereby sounds reaching said microphone are ineffective to release and start the torpedo when the relay responsiv to said radio receiving means is being energized.

light-sensitive device is receiving light of predetermined intensity.

13. In a torpedo, propelling mechanism, control means electricallyoperated including a first relay for starting said propelling mechanism, a

microphone and a circuit associated therewith I :cuit of said microphone, whereby the energize.-

11. In a torpedo, rudders, moving means for turning said rudders, a source of power for said moving means, relay means controlling the .application of said source of power to said moving means, a plurality of microphones, means for energizing said relay means in response to sounds reaching said microphones ,to effect the steering of the torpedo, said lastmentioned means in!- cluding at least one thermionic'tube and at least one source of power for said tube, alight-sensitive device, and a relay actuated from said lightsensitive device, said relay acting when energized to open the circuit connecting said thermionic tube and said source of power, whereby light reaching said light-sensitive device in predeterbined intensity prevents sounds reaching said microphone from moving said rudders.

12. In a torpedo, propelling means, a source of power for said propellin means, electrically operated control means for starting said propelling means, including a first relay, said first relay acting when energized to start said propelling means, a source of power for said first relay, a second relay and a thirdrelay, an-electric circuit connecting said source of power with said first relay including the contacts of said second relay and the contacts of said third rel y, said 'second relay when energized acting to close its tion of said second relay due to light reaching said light-sensitive device in predetermined intensity prevents sounds reaching said microphone from starting the said propelling mecha-.

said first relay acting when energized to close its contacts, a source of power for said first relay, a second relay and a third relay,'an electrical circuit connecting said source of power with said first relay including the contacts of said second relay and the contacts of said third relay, said second relay when energized acting to close its contacts, said third relay when energized acting to open its contacts, a microphone, means ren-' dering said second relay energized when sounds of at least a predetermined duration reach said microphone, a light-sensitive device and means rendering said third relay energized when light reaches said light-sensitive device in predetermined intensity.

15. In a torpedo having steering means, propelling means and a source of power for said propelling means, electrically operated control means for starting said propelling means and a source of power for said electrically operated control means; means for attaching the torpedo to an object external thereto comprising a first member adapted to catch with a suitable external member, a solenoid adapted when energized to release said first member, a source of power for said solenoid, a first relay having contacts which close when the relay is energized, the contacts controlling the application of power to'said propeller control means and the application of power to said solenoid, a source of power for said first relay, a second relay and a third relay, an electric circuit connecting said source of power with said first relay including the contacts of said second relay and the contacts of said third relay, said second relay when energized acting to close its contacts,'said third relay acting when energized to open its contacts, a microphone, means rendering said second relay energized when 'sounds of at least a predetermined duration reach said microphone, a lightsensitive device, and means rendering said third relay energized when said light-sensitive device is receiving light of predetermined intensity where-'- by sounds reaching said microphone are ineflective to release and start the torpedo when the relay responsive to said light sensitive device is being energized.

16. Ina torpedo, steering means and electrically operated control means therefor, propelling mean and electrically operated control means for starting said propelling means, a plurality of microphones, an electrical circuit normally operative connecting said microphones and both of said control means to effect the starting of the torpedo upon the receipt of sounds by at least one of said microphones and the guidin of the torpedo by sounds reaching a pair of said microphones. and radio controlled means for rendering said electrical circuit inoperative upon the receipt of radio signals of predetermined duration, said last mentioned means including a radio receptive device and an electronic time-delay relay.

17. In a torpedo, steering means and electrically operated control means therefor, propelling means and electrically operated control means for starting said propelling means, a plurality of microphones, an electrical circuit normally operative connecting said microphones and both of said control means to effect the starting of the torpedo upon the receipt of sounds by at least one of said microphones and the guiding of the torpedo by sounds reaching a pair of said microphones, and radio controlled means for rendering said elec- 10 trical circuit inoperative upon the receipt of radio signals of predetermined character including an audio frequency bridge circuit and apparatus associated therewith adapted to be operated when said bridge is unbalanced.

MAURY I. HULL. 

